1. Field of the Invention
The present invention relates generally to the field of electronic function cards for use in data processing systems. More particularly, the present invention relates to an apparatus and method for retaining an electronic function card in a receptacle of a data processing system.
2. Description of the Related Art
Data processing systems have been configured for use with electronic function cards that provide increased functionality for the data processing system. Electronic function cards typically contain a printed circuit board having electronics and circuitry to implement their functionality. Such cards may be used to provide increased memory or storage capacity for the data processing system. Electronic function cards may also be used to provide for communications capabilities for the data processing system with external hosts, data processing systems, or networks. The cards provide convenience for users of a data processing system by allowing the user to install additional capabilities or features as needed.
Electronic function cards are typically portable cards that may be inserted into and detached from a receptacle housed within the host data processing system (or a host socket). The Personal Computer Memory Card International Association (PCMCIA) has devised standards for electronic function cards to provide compatibility between various data processing systems and various electronic function cards. The PCMCIA standards specify a 68-pin connector at one end of a PCMCIA card for insertion into a compatible receptacle in the host data processing system (or host socket). When inserted into the host socket, the card is held in place by the frictional force exerted on each of the 68 pins of the card connector.
Many new cards, such as flash memory cards, small form factor cards, miniature cards, and smart cards, are being made with substantially fewer contact pins even though in many cases the size or mass of the card remains the same. In other words, the number of contact pins is being reduced faster than the size or weight of the card. With fewer contact pins engaged, there is a correspondingly smaller frictional force (or retention force) exerted on the electronic function card to retain the card in the host socket. With smaller retention forces, the card can become dislodged from the host socket more easily during mechanical shock events, such as when the data processing system is dropped or jostled.
To prevent a card from becoming dislodged as the pin count of the card is reduced, the weight of the card must be reduced by the same percent reduction as the pin count reduction. With a card of PCMCIA size having only 34 pins, the weight of the card per pin has doubled when compared to a PCMCIA card. The added weight per pin can cause a problem in retaining the card in the host socket. Often, however, it is not possible to reduce the weight of the card even when the card""s pin count has been reduced. Similarly, additional electronics may be added to a standard PCMCIA card or attachments may be coupled to the card, both of which add weight to the card and increase the card weight per pin. Thus, a low cost feature that may be added to the card to increase the retention forces on the card and reduce the chance of the card dislodging from its host socket is desirable. With such a feature, low pin count cards (those having less than the standard 68 pins) and cards having attachments or added weight may have similar resistance to becoming dislodged as a PCMCIA card.
Further, current card and host socket interconnections do not employ direct feedback during insertion operations to indicate when the card is fully inserted into the host socket. Often, when a PCMCIA card is inserted into a host socket, the system xe2x80x9csensesxe2x80x9d that the card is inserted and, typically after a time delay, the system responds with an auditory feedback, such as a beep. However, the feedback can occur when the electrical contacts are just starting to make contact. In other words, the card does not have to be fully inserted for the system to signal that the insertion is complete. A premature signal can result in a risky connection, in that small movements, such as vibrations, may cause the card to be disconnected from one or more contacts.
Attempts to solve the premature feedback are flawed due to inadequate specifications for the card connector contact design. For example, the PCMCIA""s sequential connection scheme using multiple length pins in the host socket has not been successful. Thus, it is desirable to have a tactile and/or auditory feedback signal to clearly indicate to the user when the card has been fully inserted into the host socket.
The present invention describes a method and apparatus for increasing the retention forces exerted on an electronic function card inserted into a receptacle of a data processing system (or host socket) to reduce the chance of the card dislodging from the host socket. The present invention may be comprised of an electronic function card having at least one spring-loaded button on the card casing. The host socket for the card has a corresponding indention on the host socket such that when the card is inserted into the host socket, the spring-loaded button will snap into place and reside within the corresponding indention. The spring loaded button and indention combination may be reversed such that the indention is a part of the card casing and the spring-loaded button is a part of the host socket. The button or indention may be placed at one or more locations on the card casing, with corresponding indention(s) or button(s) located on the host socket. A second embodiment of the present invention exerts a retention force on a card using a spring-loaded arm extending from the host socket. The spring-loaded arm has at least one stop that conforms with the contour of the card to securely hold the card in place. Both embodiments of the present invention exert a retention force on the card in addition to the frictional force exerted on the card connector pins to reduce the chance of the card dislodging from the host socket during a mechanical shock event.